Solid state drawing laminated polymer billets

ABSTRACT

Solid state draw a laminated polymer billet containing two or more polymer compositions laminated to one another to prepare an oriented polymer composition.

CROSS REFERENCE STATEMENT

This application is a National Phase application of InternationalApplication No. PCT/US2010/020026, filed Jan. 4, 2010, which claims thebenefit of U.S. Provisional Application No. 61/144,764, filed Jan. 15,2009, both of which are incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid state drawing process forpolymer billets and oriented polymer compositions resulting from thedrawing process.

2. Description of Related Art

Cross sectional dimensions of a polymer composition necessarily reduceupon drawing the polymer composition. That means that the final drawnarticle will have smaller cross sectional dimensions than the polymercomposition prior to drawing. In drawing films or small dimensionarticles such a reduction in cross sectional dimensions is notparticularly problematic. However, when trying to draw a polymercomposition into a final drawn article having large cross sectionaldimensions the process can become cumbersome because it requires billetshaving very large dimensions prior to drawing. The problem isparticularly evident when trying to combine into a continuous processboth extrusion of an initial polymer billet and drawing the polymerbillet. Consider, for example, a solid state drawing process forpreparing articles in the form of oriented polymer compositions (OPCs).

A solid state drawing process typically requires extruding a polymerbillet, conditioning that polymer billet to a drawing temperature andthen drawing the polymer billet to obtain an OPC. Generally, a billet isat a higher temperature upon extrusion than the target drawingtemperature for the billet, so thermally conditioning the billet isnecessary. Conditioning the billet to a uniform drawing temperature isnecessary to achieve uniform orientation throughout the resulting OPCafter drawing. However, rapidly cooling an extruded billet to a uniformtemperature becomes increasingly challenging as the cross section of thebillet increases. The core temperature of a billet is dependent on thedifference in temperature between the core and the surface, the distancefrom the surface to the core, the heat transfer coefficient of thebillet material and the heat transfer coefficient at the surface whereheat is being removed from the billet. The greater the distance from thesurface to the core the more time is necessary to reach a uniformtemperature across a billet cross section (equilibrium temperature). Forexample, the cooling rate of a solid having an infinite width (that is,no edge effects considered) is proportional to the square of thedistance form the surface to the core (see, for example, J. L. Throne,THERMOFORMING, Chapt. 3, pp 65, Hanser Publisher, Numich, 1987).Nonetheless, rapid cooling of a billet to a uniform cross sectionaltemperature equal to a drawing temperature is necessary if extrusion anddrawing are to occur together in a continuous process at a reasonableproduction rate and with a reasonable equipment footprint.

Methods of actively cooling a billet upon extrusion are known. Forinstance, an early reference describing an OPC drawing process describesexposing a polymer billet to a chilled water bath immediately upondrawing (see, Ward, et al., SOLID PHASE PROCESSING OF POLYMERS, Hanserpublishing, Munich (2000), Chapter 9 page 359). Other references merelydescribe “adjusting the temperature” of a billet to a drawingtemperature, a process that typically requires heating a billet to adrawing temperature (see, for example, United States patent application2005/0192382). Modifying the temperature of a billet's surface can occurrelatively rapidly, but creates a thermal gradient between the billet'ssurface and the billet's core. As a result, adjusting the temperature(or “conditioning”) a billet to a drawing temperature often requiressuper cooling the billet surface until the core reaches a temperatureclose to the drawing temperature and then reheating the billet exteriorto bring the surface portion back up to the drawing temperature. Coolingthe core of a billet takes more time as the billet cross sectionincreases. Therefore, conditioning a billet to a drawing temperature canbe time consuming for large cross section billets.

In a continuous process, an extruded billet must undergo temperatureconditioning to its drawing temperature as it travels from an extruderto a drawing device. As the time for temperature conditioning increaseswith large cross section billets, the distance between the extruder anddrawing device must also increase or the production rate must slow down.Therefore, continuous processes for preparing and drawing large crosssection billets can require extremely long process lines or extremelylow production rates. It is desirable to more efficiently condition anextruded billet to a drawing temperature in a manner that can be part ofa continuous process of preparing a billet and then drawing the billetto prepare an OPC.

BRIEF SUMMARY OF THE INVENTION

The present invention advances the art of producing OPCs by offering anefficient process for producing OPCs that reduces the time necessary forconditioning the temperature of a billet from it extrusion temperatureto a drawing temperature.

In a first aspect, the present invention is a process for solid diedrawing a large dimensioned oriented polymer comprising the followingsteps in order, optionally with other steps existing between any twosteps: (a) extruding from an extruder a first orientable polymercomposition having a surface and core where the first orientable polymercomposition, including its surface and core, is at an extrusiontemperature; (b) cooling the first orientable polymer composition sothat its surface is at a temperature below the extrusion temperature;(c) providing a second polymer composition and laminating the secondpolymer composition to a surface of the first orientable polymercomposition to form a laminated billet; (d) conditioning the laminatedbillet to a drawing temperature that is lower than the extrusiontemperature if the laminated billet is not already at the drawingtemperature; and (e) drawing the laminated billet through a solid statedrawing die to form an oriented polymer composition having all crosssectional dimensions greater than 1.5 mm. Optional additional polymercompositions that may be orientable can be incorporated into thelaminated billet by repeated step (c) to add a third or fourth or anynumber of polymer compositions prior to step (d).

Embodiments of the first aspect can comprise any one or combination ofmore than one of the following characteristics: the first orientablepolymer composition extends continuously from the extruder until afterstep (e); the second polymer composition is an orientable polymercomposition; the first orientable polymer composition comprises acontinuous orientable polymer phase comprising one or more than one ofpolypropylene, polyethylene, polyester and polyvinyl chloride; thesecond polymer composition has a composition that is the same as thefirst orientable polymer composition; both the first orientable polymercomposition and the second polymer composition are extruded at anextrusion temperature from the same extruder and through a singleextrusion die but through different orifices in the extrusion die andwherein the second polymer composition also undergoes a cooling step toa temperature that is below its extrusion temperature prior to step (c);the second polymer composition comes from a second extruder at a secondextrusion temperature and is cooled to a temperature that is below thesecond extrusion temperature before step (c); the second polymercomposition has a composition that is different from the firstorientable polymer composition; the second polymer composition is otherthan an extruded polymer composition; cooling in step (b) includesapplication of a fluid cooling medium to the first orientable polymercomposition; both the first orientable polymer composition and thesecond polymer composition are conditioned to the drawing temperatureprior to adhering them together to form a laminated billet; both thefirst orientable polymer composition and second polymer composition havea softening temperature and wherein step (c) includes heating thesurface of one or both of the polymer compositions to a temperatureabove its softening temperature and then contacting the surface of thefirst orientable polymer composition with the second polymer compositionin order to achieve a melt-weld between the two polymer compositions andoptionally applying pressure so as to compress the first orientablepolymer composition and the second polymer composition together as theymelt-weld; the first orientable polymer composition and the secondpolymer composition each have a surface and step (c) comprises applyingan adhesive to the surface of one or both of the first orientablepolymer composition and the second polymer composition and thencontacting the surface together so that the adhesive adheres the firstorientable polymer composition and second polymer composition together;the first orientable polymer composition, the second polymer compositionor both are laminated billets; step (e) includes drawing the laminatedbillet through a solid state drawing die; step (e) induces bothorientation and cavitation in at least the first orientable polymercomposition; and either or both of the first orientable polymercomposition and the second polymer composition comprise inorganic fillerdispersed within them.

In a second aspect, the present invention is a solid state die drawnoriented polymer composition comprising at least two laminated polymercompositions where at least one of the two laminated polymercompositions is oriented, and wherein the at least two laminated polymercompositions are melt-welded together as evidenced by a melt-weld lineat the interface of the at least two laminated polymer compositions.

Embodiments of the second aspect can comprise any one or any combinationof more than one of the following characteristics: at least one orientedpolymer composition is cavitated; both laminated polymer compositionsare of the same composition and are both oriented; the laminated polymercompositions are melt-welded together as evidenced by a melt-weld lineat their interface; and the two laminated polymer compositions differ inat least one characteristic selected from a group consisting of extentof orientation, composition, color and extent of cavitation.

A solid state die drawn large dimensioned oriented polymer compositioncomprising at least two laminated polymer compositions where at leastone of the two laminated polymer compositions is oriented, and whereinall cross sectional dimensions of the oriented polymer composition aregreater than 1.5 mm.

Surprisingly, the process of the present invention can produce an OPChaving an appearance and properties that are similar to that of an OPCprepared from a single extruded billet, yet uses a fraction of thefootprint such a process would require.

Moreover, the process of the present invention offers an ability toprepare OPCs having structures uncharacteristic of OPCS from a singleextruded billet. For example, the present invention allows forcontinuous fabrication of OPCs having zones of different materials by,for example, laminating layers of different polymer compositionstogether to form a billet just prior to drawing the billet into an OPC.

The present invention is useful for preparing OPCs of the presentinvention. OPCs of the present invention are useful for applicationssuch including rail road ties, large planks, telephone poles, siding,decking materials, fencing materials, decorative trim materials and as awood replacement in essentially any wood application.

DETAILED DESCRIPTION OF THE INVENTION Terms

“Polymer composition” comprises a continuous polymer phase containing atleast one polymer component and can contain non-polymeric components. A“filled” polymer composition includes discontinuous additives, such asinorganic fillers and/or crosslinked rubber particles, in the polymercomposition.

An “orientable polymer” is a polymer that can undergo induced molecularorientation by solid state deformation (for example, solid statedrawing). An orientable polymer can be amorphous or semi-crystalline(semi-crystalline polymers have a melt temperature (T_(m)) and includethose polymers known as “crystalline”). Desirable orientable polymersinclude semi-crystalline polymers, even more desirable are linearpolymers (polymers in which chain branching occurs in less than 1 of1,000 polymer units). Semi-crystalline polymers are particularlydesirable because they result in greater increase in strength andmodulus than amorphous polymer compositions. Semi-crystalline polymercompositions can result in 4-10 times greater increase in strength andflexural modulus upon orientation over amorphous polymer compositions.

An “orientable polymer phase” is a polymer phase that can undergoinduced molecular orientation by solid state deformation (for example,solid state drawing). Typically, 75 weight-percent (wt %) or more, even90 wt % or more or 95 wt % or more of the polymers in the orientablepolymer phase are orientable polymers based on total orientable polymerphase weight. All of the polymers in an orientable polymer phase can beorientable polymers. An orientable polymer phase may comprise one ormore than one type of polymer and one or more than one type oforientable polymer.

An “orientable polymer composition” is a composition that comprises anorientable polymer in a continuous orientable polymer phase and,optionally, other components such as additives.

“Oriented polymer composition” and “OPC” are interchangeable and referto an orientable polymer composition having orientable polymers thathave been oriented to form an article. To be clear, and OPC is anarticle rather than a mere polymer composition. An OPC requiresprocessing a polymer composition to orient polymers therein and therebyconverts the polymer composition to an article, an OPC.

“Cross sections” of an OPC are perpendicular to the orientationdirection of the OPC unless the reference to the cross section indicatesotherwise. A cross section has a centroid, a perimeter and dimensionsthat extend through the centroid and connect two points on theperimeter.

Cross sectional dimension extends in a straight line in a cross sectionof an OPC connecting two points on a surface of the OPC and extendingthrough the centroid of the cross section in which it resides.

The surface of a polymer composition includes an exposed portionextending two or more dimensions of the polymer composition. The surfaceextends radially from the exposed portion towards the centroid to adepth of 0.5 centimeters or one third of the distance to the centroid,whichever is less.

The core of a polymer composition comprise the centroid of any crosssection of the polymer composition and extends radially out from thecentroid towards a surface of the polymer composition to a distance ofcentimeter or one third the distance to the surface, whichever is less.

In regards to reference to a polymer composition temperature, an artisanunderstands that a polymer composition typically has a variation intemperature through a cross section (that is, along a cross sectionaldimension of the composition) during processing. Therefore, reference totemperature of a polymer composition refers to an average of the highestand lowest temperature along a cross sectional dimension of the polymercomposition. The temperature at two different points along the polymercross sectional dimension desirably differs by 10% or less, preferably5% or less, more preferably 1% or less, most preferably by 0% from theaverage temperature of the highest and lowest temperature along thecross sectional dimension. Measure the temperature in degrees Celsius (°C.) along a cross sectional dimension by inserting thermocouples todifferent points in the cross sectional dimension.

“Solid state” refers to a polymer (or polymer composition) that is at atemperature below the softening temperature of the polymer (or polymercomposition). Hence, “solid state drawing” refers to drawing a polymeror polymer composition that is at a temperature below the softeningtemperature of the polymer (or polymer composition).

“Softening temperature” (T_(s)) for a polymer or polymer compositionhaving as polymer components only one or more than one semi-crystallinepolymer is the melting temperature for the polymer composition.

“Melting temperature” (T_(m)) for a semi-crystalline polymer is thetemperature half-way through a crystalline-to-melt phase change asdetermined by differential scanning calorimetry (DSC) upon heating acrystallized polymer at a specific heating rate. Determine T_(m) for asemi-crystalline polymer according to the DSC procedure in ASTM methodE794-06. Determine T_(m) for a combination of polymers and for a filledpolymer composition also by DSC under the same test conditions in ASTMmethod E794-06. Determine T_(m) using a heating rate of 10 degreesCelsius (° C.) per minute. If the combination of polymers or filledpolymer composition only contains miscible polymers and only onecrystalline-to-melt phase change is evident in its DSC curve, then T_(m)for the polymer combination or filled polymer composition is thetemperature half-way through the phase change. If multiplecrystalline-to-melt phase changes are evident in a DSC curve due to thepresence of immiscible polymers, then T_(m) for the polymer combinationor filled polymer composition is the T_(m) of the continuous phasepolymer. If more than one polymer is continuous and they are notmiscible, then the T_(m) for the polymer combination or filled polymercomposition is the lowest T_(m) of the continuous phase polymers.

T_(s) for a polymer or polymer composition having as polymer componentsonly one or more than one amorphous polymer is the glass transitiontemperature for the polymer composition.

“Glass transition temperature” (T_(g)) for a polymer or polymercomposition is as determined by DSC according to the procedure in ASTMmethod E1356-03. Determine T_(g) for a combination of polymer and for afilled polymer composition also by DSC under the same test conditions inASTM method E1356-03. If the combination of polymer or filled polymercomposition only contains miscible polymers and only one glasstransition phase change is evident in the DSC curve, then T_(g) of thepolymer combination or filled polymer composition is the temperaturehalf-way through the phase change. If multiple glass transition phasechanges are evident in a DSC curve due to the presence of immiscibleamorphous polymers, then T_(g) for the polymer combination or filledpolymer composition is the T_(g) of the continuous phase polymer. Ifmore than one amorphous polymer is continuous and they are not miscible,then the T_(g) for the polymer composition or filled polymer compositionis the lowest T_(g) of the continuous phase polymers.

If the polymer composition contains a combination of semi-crystallineand amorphous polymers, the softening temperature of the polymercomposition is the softening temperature of the continuous phase polymeror polymer composition. If the semi-crystalline and amorphous polymerphases are co-continuous, then the softening temperature of thecombination is the lower softening temperature of the two phases.

“Drawing temperature”, (T_(d)), is a temperature within a drawingtemperature range at which a polymer is conditioned prior to drawing andis the temperature at which the polymer exists upon the initiation ofdrawing.

“Weight-percent” and “wt %” are interchangeable and are relative tototal polymer weight unless otherwise stated.

“ASTM” refers to an American Society for Testing and Materials testmethod. The year of the method is either designated by a hyphenatedsuffix in the method number or, in the absence of such a designation, isthe most current year prior to the filing date of this application.

“Multiple” means at least two. “And/or” means “and, or as analterative.” Ranges include endpoints unless otherwise stated.

The process of the present invention is a method of producing anoriented polymer composition (OPC). The process is particularly usefulin preparing OPCs of large dimensions including telephone poles,railroad ties and materials of similar or even larger dimensions.Nonetheless, the process is also useful for preparing OPCs of smalldimensions more efficiently that prior processes. There is no limitationon what dimension OPC the present process can produce.

The process requires that the following steps occur in a particularorder. That means that one of the steps cannot occur before another stepin the order. However, additional steps may optionally be includedin-between any two steps and the two steps are still considered asoccurring in order. That is, requiring that steps occur in order doesnot require that the steps occur one directly after the other withoutintervening steps.

The first required step is to extrude from an extruder a firstorientable polymer composition having a surface and core where the firstorientable polymer composition, including its surface and core is at anextrusion temperature. The extrusion temperature is higher than thesoftening temperature of the first orientable polymer composition and isthe temperature at which the first orientable polymer composition exitsthe extruder. Generally, there is some type of extrusion die on the endof the extruder through which the first orientable polymer compositionis extruded. The first orientable polymer composition is typically atthe extrusion temperature upon exiting the extrusion die.

The first orientable polymer composition comprises a continuousorientable polymer phase. The orientable polymers in the orientablepolymer phase may be amorphous, semi-crystalline (semi-crystallinepolymers are those having a melt temperature (T_(m))), or a combinationof amorphous and semi-crystalline. Desirably the orientable polymerphase comprises one or more than one semi-crystalline polymer and,preferably, the one or more than one semi-crystalline polymer that iscontinuous throughout the continuous orientable polymer phase.

Suitable orientable polymers include polymers and copolymers based onpolypropylene, polyethylene (e.g., high density polyethylene),polymethylpentane, polytetrafluoroethylene, polyamides, polyesters,polycarbonates, polyethylene oxide, polyoxymethylene, polyvinylchloride, polyvinylidene fluoride polymers having a weight-averagemolecular weight of from 200,000 to 800,000 g/mol, preferably 250,000 to400,000 g/mol, liquid crystal polymers and combinations thereof.

Desirable orientable polymers include polymers based on polyethylene,polypropylene, polyester (for example, polyethylene terephthalate) andpolyvinyl chloride polymers. A first polymer is “based on” a secondpolymer if the first polymer comprises monomer repeat units of thesecond polymer. For example, a block copolymer is based on the polymerscomprising the blocks. More particularly desirable orientable polymersinclude linear polyethylene having a weight-average molecular weight(Mw) from 50,000 to 3,000,000 g/mol; especially from 100,000 to1,500,000 g/mol, even from 750,000 to 1,500,000 g/mol.

Particularly desirable orientable polymers include polyolefin polymers(polyolefins). Polyolefins tend to be more likely to undergo cavitation,particularly in combination with filler particles presumably becausepolyolefins are relatively non-polar and as such adhere less readily tofiller particles. Linear polymers (that is, polymers in which chainbranching occurs in less than 1 of 1,000 polymer units) are even moredesirable.

Polypropylene (PP)-based polymers (that is, polymers based on PP) areespecially desirable for use in the present invention. PP-based polymersgenerally have a lower density than other orientable polyolefinpolymers. Therefore, PP-based polymers facilitate lighter articles thanother orientable polyolefin polymers. PP-based polymers also offergreater thermal stability than other orientable polyolefin polymers.Therefore, PP-based polymers may also form oriented articles havinghigher thermal stability than oriented articles of other polyolefinpolymers.

Suitable PP-based polymers include Zeigler Natta, metallocene andpost-metallocene polypropylenes. Suitable PP-based polymers include PPhomopolymer; PP random copolymer (with ethylene or other alpha-olefinpresent from 0.1 to 15 percent by weight of monomers); PP impactcopolymers with either PP homopolymer or PP random copolymer matrix of50 to 97 percent by weight (wt %) based on impact copolymer weight andwith ethylene propylene copolymer rubber present at 3 to 50 wt % basedon impact copolymer weight prepared in-reactor or an impact modifier orrandom copolymer rubber prepared by copolymerization of two or morealpha olefins prepared in-reactor; PP impact copolymer with either a PPhomopolymer or PP random copolymer matrix for 50 to 97 wt % of theimpact copolymer weight and with ethylene-propylene copolymer rubberpresent at 3 to 50 wt % of the impact copolymer weight added viacompounding, or other rubber (impact modifier) prepared bycopolymerization of two or more alpha olefins (such as ethylene-octene)by Zeigler-Natta, metallocene, or single-site catalysis, added viacompounding such as but not limited to a twin screw extrusion process.Particularly desirable is PP homopolymer or a random copolymer ofpropylene (PP-based copolymer) with 0.5 to 5 percent by weight ethylene.

Suitable PP-based polymers can be ultra-violet (UV) stabilized, anddesirably can also be impact modified. Particularly desirable PP-basedpolymers are stabilized with organic stabilizers. The UV stabilizedPP-based polymers can be free of titanium dioxide pigment therebyallowing use of less pigment to achieve any of a full spectrum ofcolors.

The first orientable polymer composition can comprise one or more thanone additive, or filler, in addition to the orientable polymer. Fillerscan be organic, inorganic or a combination of organic and inorganic.

Cellulosic fillers are one type of organic filler. Cellulosic fillerssuch as wood fiber and powder are known in oriented polymer compositionshaving large cross sections (that is, cross sectional dimensions allgreater than 1.5 mm). However, wood fiber and cellulosic materials ingeneral, are susceptible to color bleaching when exposed to the sun, andto decomposition, mold and mildew, and microbial activity when exposedto humidity even when used as filler within a polymer composition. Thesefeatures are handicaps that can render cellulosics undesirable for usein filled polymer compositions exposed to sun and humidity.

Inorganic materials do not suffer from the handicaps of cellulosics.Therefore, inorganic filler can be more desirable than cellulosicfillers for use in oriented filled polymer compositions. Inorganicfiller may be reactive or inert. Reactive fillers react with water andinclude materials such as Portland cement and gypsum. Inert fillers donot react with water. Inert inorganic fillers are more desirable forachieving a stable polymer composition density because polymercomposition containing the filler density is less likely to change uponexposure to moisture than with reactive filler. Suitable inert inorganicfillers include talc (including any or a combination of material gradescommonly known and available as “talc”), fly ash, calcium carbonate,clay (for example, kaolin), dolomite, glass beads, silica, mica, metal,feldspar, carbon black, nano-fillers, Wollastonite, glass fibers, metalfibers, and boron fibers. Particularly desirable inorganic fillersinclude talc and calcium carbonate.

The optimum amount of filler in the polymer composition of the presentprocess depends on target properties for the final oriented polymercomposition. Low levels of filler results in low levels of cavitation(that is, low void volumes due to cavitation). Excessive levels offiller can reduce a polymer composition's strength if the polymerbecomes discontinuous in the polymer composition. Typically, the amountof filler is 20 weight-percent (wt %) or more, preferably 30 wt % ormore, more preferably 40 wt % or more and most preferably 45 wt % ormore. Filler can be present in an amount of 60 wt % or more, even 70 wt% or more. Generally, the amount of filler is 90 wt % or less. If filleris present at a concentration exceeding 90 wt % the polymer compositiontends to undesirably lose structural integrity. Determine wt % of fillerbased on the weight of polymer composition before drawing.

The second step of the present process is cooling the first orientablepolymer composition so that its surface is at a temperature below theextrusion temperature. Ideally, the cooling step results in cooling thefirst orientable polymer composition sufficiently so that its core iswithin 20° C., preferably within 15° C., more preferably within 10° C.and still more preferably within 5° C. of the drawing temperature. Anobjective of the cooling step is to bring the first orientable polymercomposition close to a desirable drawing temperature before increasingits thickness by lamination. An advantage of the present invention isthat multiple orientable polymer compositions can be cooled to atemperature close to a desirable drawing temperature more quickly than asingle orientable polymer composition having a thickness equal to acombination of the multiple orientable polymer compositions. Cooling theorientable polymer compositions individually and then laminating themtogether allows for production of a thick orientable polymer compositionnear a desirable drawing temperature faster than if the thick orientablepolymer composition was extruded and cooled as a single composition. Thecooling step can be immediately followed by a heating the surface of theorientable polymer composition to a temperature proximate to (within 20°C., preferably within 15° C., more preferably within 10° C. and stillmore preferably within 5° C. of) the drawing temperature prior to thethird step. The cooling and heating together serves as a temperatureconditioning step.

Cool the orientable polymer composition in any of a number of ways, orby a combination of multiple ways. One desirable method of cooling is tospray a cooling fluid over the orientable polymer composition. Anotherdesirable method of cooling is to transfer the orientable polymercomposition through a bath of cooling fluid. Suitable cooling fluidsinclude water, water based solutions, oil, and air or other gas.

The third step in the present process is to provide a second polymercomposition and adhere the second polymer composition to a surface ofthe first orientable polymer composition to form a laminated billet. Inthe present context, “laminated billet” merely refers to a billetcomprising two or more compositions adhered together. Desirably, but notnecessarily, one polymer composition completely covers a surface ofanother polymer composition in the laminated billet.

The second polymer composition may be an orientable polymer composition(second orientable polymer composition) or may be other than anorientable polymer composition. If the second polymer composition is asecond orientable polymer composition, it is subject to the samecomposition teachings as the first orientable polymer composition.Nonetheless, the second polymer composition may have the samecomposition or a composition different from the first orientable polymercomposition within the scope of those teachings. In one embodiment, thesecond polymer composition is a second orientable polymer compositionand both the first and second orientable polymer compositions areconditioned to a drawing temperature prior to adhering to one another toform a laminated billet.

The second orientable polymer composition may be identical to the firstorientable polymer composition. In fact, both the first and secondorientable polymer compositions can come from the same extruder througha die that has two or more orifices wherein the first orientable polymercomposition exits the extruder through one orifice and the secondorientable polymer composition exits the extruder through anotherorifice. Both the first and second orientable polymer compositionsdesirably undergo cooling to a temperature below the extrusiontemperature prior to adhering to one another to form the laminatedbillet.

In an alternative embodiment, the second orientable polymer compositionmay be an extruded polymer composition that comes from a second extruderat a second extrusion temperature and is cooled to a temperature that islower than the second extrusion temperature before, even just prior, toadhering to a surface of the first orientable polymer composition. Inthis embodiment, two orientable polymer compositions may be the same ordifferent in composition even though they are both orientable.

The second polymer composition does not need to be an orientable polymercomposition. The second polymer composition can be non-orientablepolymer billet (that is, a billet that does not have a continuous phaseof orientable polymer) or can be an orientable polymer billet(composition). The second polymer composition can also be a polymer filmor even a polymer coating applied in spray or other coating form.

Adhere the second polymer composition to the first orientable polymercomposition preferably by melt welding or by using an appropriateadhesive. Melt weld the two compatible polymer compositions together bycontacting their surfaces together while the surfaces are at or,desirably, above their softening temperature. It is desirable to havethe surface temperatures at least 10° C. above their softeningtemperature to optimize the strength of the melt weld. Melt weldingoccurs when polymer chains from one polymer composition entangle withpolymer chains form the other polymer composition and vice versa. Thepolymer compositions must be compatible for melt welding to occur. Twopolymer compositions are compatible if their polymer chains willintermingle with one another. The surfaces of the polymer compositionswill desirably be at a temperature below the softening temperature soheating of the surfaces is generally necessary. Any method of heating isacceptable including exposing to hot air, radiant heat, or even directcontact with a hot element such as a platen. Contact the surfacestogether while they are at a temperature above their softening pointand, preferably, apply pressure to compress the surfaces together for aperiod of time (for example, up to 60 seconds) to achieve a melt weld.One method of applying pressure is to run the two compositions betweennip rollers or spaced apart opposing belts.

Use of adhesives is less desirable but a possible method of forming alaminated billet from the first orientable polymer composition and thesecond polymer composition. A challenge with using adhesives isselecting an adhesive that adheres to both the first orientable polymercomposition and the second polymer composition and that maintainsadhesion through the drawing of the laminated billet. Selection of anappropriate adhesive will depend on the composition of the two polymercompositions the adhesive will adhesively join. Select an adhesive thatadheres to both polymer compositions. Also choose an adhesive that candeform instead of break or fracture during the solid state drawing step.The adhesive is desirably a thermoplastic material, or at least hasthermoplastic properties throughout the drawing process. When using anadhesive, apply the adhesive to one or preferably both surfaces beingadhered together and then contact the surfaces to one another,preferably while applying pressure. Use of a tie layer may be desirablefor billet materials that are adhesively incompatible. For example, atie layer may adhere to one billet with one adhesive and another billetwith a different adhesive thereby adhering the billets to one another.

This third step of providing a second polymer composition and adheringit to a surface of the first polymer composition offers flexibility inthe composition of pre-drawn billets that is otherwise unknown. Forexample, a billet prior to drawing that contains multiple polymercompositions is achievable, as is a drawn OPC comprising multiplepolymer compositions in specific locations of the OPC, through theprocess of the present invention. The laminated billet may comprisemultiple polymer compositions adhered in various desirableconfigurations with the first orientable polymer compositions in orderto provide desirable properties at various locations in a cross sectionof an OPC. Of course, even if the polymer compositions adhered togetherto form the laminated billet are identical, the present invention stilloffers the advantage of providing a large dimension pre-drawn billet ata drawing temperature more quickly than is possible by providing asingle billet of the same large dimension directly from an extruder.Surprisingly, the resulting laminated billet can be drawn into an OPCwithout fracturing or failure despite the extreme forces the billetexperiences in a drawing process.

The fourth required step is to condition the laminated billet to adrawing temperature that is lower than the extrusion temperature if thelaminated billet is not already at the drawing temperature. It ispossible that upon forming the laminated billet, the laminated billet isalready at a drawing temperature. However, it is also possible that thelaminated billet needs conditioning to a drawing temperature. Conditionthe temperature of the laminated polymer billet as necessary to achievedrawing temperature. Desirably, little if any conditioning is necessaryas much of the temperature modification is desirably done prior toforming the laminated billet.

The fifth step in the present process is to draw the laminated billet toform an oriented polymer composition. Drawing a laminated billetrequires applying a tensile force to the laminated billet and stretchingthe laminated billet in the tensile direction. Drawing processes aredistinct from orientation processes that only apply pressure to extrudepolymer compositions. The tensile force draws a polymer composition,inducing polymer orientation while also facilitating cavitation of thepolymer composition during orientation. The present process requiresapplying a tensile force.

Draw the laminated billet while the billet is in a solid state. Solidstate drawing desirably results in alignment, or orientation, of theorientable polymers in the laminated billet. The orientable polymers inthe orientable polymer phase of the first orientable polymer compositionundergo orientation during the drawing process. If the second polymercomposition also comprises orientable polymers, they also desirablyundergo orientation during drawing. In a preferred embodiment,cavitation occurs in the laminated billet during the drawing process.Cavitation is an introduction of void volume dispersed within a polymercomposition as polymer is drawn away from filler particles, polymercrystallites or other inhomogeneities in the polymer composition.Cavitation can occur in one polymer composition or more than one polymercomposition making up the laminated billet. For example, cavitation mayonly occur in the first orientable polymer composition, only the secondpolymer composition or in both the first and the second polymercomposition during drawing depending on the make-up of the polymercompositions and the drawing conditions (for example, faster drawingrates are more likely to induce cavitation than slower drawing rates).

In a preferred embodiment, draw the laminated polymer compositionthrough a solid state drawing die. Solid state drawing dies have aconverging die channel through which a polymer composition is drawn. Theshape of the die channel directs the polymer composition to a specificshape during drawing. Solid state drawing dies offer greater controlthan free drawing processes. Free drawing processes are those that drawa polymer composition apart from application of constraining force on apolymer composition during the drawing process. Typically, some freedrawing occurs in die drawing processes after a polymer compositionexits the drawing die resulting in a combination of die drawing and freedrawing.

The drawing rate is sufficient to induce orientation of the polymercomposition and will depend on the polymer composition, drawingtemperature and desired properties for the resulting OPC. Desirably, thedrawing rate is at least 2.54 centimeters (one inch) per minute and istypically 91 centimeters (36 inches) per minute or faster. Particularlydesirable is a drawing rate of at least 127 centimeters (50 inches) perminute since the extent of cavitation has been found to level off atthat rate so consistent OPC density is more likely to occur at a drawingrate of 127 centimeters (50 inches) per minute or faster. (See, forexample, teaching in United States patent application 2008-0111278,incorporated herein in its entirety). An upper limit for the drawingrate is limited primarily by the drawing force necessary to achieve aspecific draw rate. The drawing force should be less than the tensilestrength of the polymer composition in order to avoid fracturing thepolymer composition. Typically, the drawing rate is 30.5 meters (1200inches) per minute or less, more typically 9 meters (360 inches) perminute or less.

The process of the present invention prepares an oriented polymercomposition comprising at least two laminated polymer compositionswherein at least one, preferably both of the polymer compositions isoriented. The oriented polymer composition is desirably cavitated. Thelaminated polymer compositions can both be oriented and can be ofidentical composition, even extruded from the same extruder through asplit die. Alternatively, the laminated polymer compositions can differin at least one characteristic selected from a group consisting ofextent of orientation, composition, color and extent of cavitation. Whenthe polymer compositions are melt-welded together during the processthere is a melt-weld line at the interface of the laminated polymercompositions. The melt-weld line is apparent under magnification of across section of the oriented polymer composition and in somecircumstances can be apparent to an unaided eye.

While the present process has been described in the context oflaminating two polymer compositions, a first orientable polymercomposition and a second polymer composition, it is conceivable andentirely within the scope of the present invention for the processes toinclude forming a laminate billet having more than two polymercompositions laminated together prior to drawing. For example, the firstorientable polymer composition may itself be a laminated billetcomprising two or more polymer compositions adhered to one another.Similarly, the second polymer composition may be a laminated billetcomprising two or more polymer compositions adhered to one another.Additional steps may exist in the present process that includes adheringone or more than one additional polymer composition to one or more ofthe first orientable polymer composition and second polymer composition.For example, after the third step of forming a laminated billet from thefirst orientable polymer composition and the second polymer compositionthere may exist one or more combinations of steps similar to the secondand third steps where a third polymer composition, fourth polymercomposition, fifth polymer composition, and so on may be adhered to thelaminated billet to form yet another more complex laminated billet priorto drawing. The third, fourth, fifth and so on polymer compositions canbe as described for the second polymer billet and may be the same ordifferent from any other polymer composition in the laminated billet.

The present process is desirably a continuous process. That means thatthe first orientable polymer composition remains as a continuous billetextending from the extruder until after drawing occurs. Such acontinuous process becomes particularly challenging to construct aspolymer cross sectional dimension become large due to the time needed tocondition a polymer billet from its extrusion temperature to the drawingtemperature prior to drawing. Extruding a large cross section polymercomposition would require a long time to condition the temperature ofthe composition to a drawing temperature. By laminating multiple polymercompositions together after conditioning their temperature the timeneeded between extrusion and drawing is dramatically reduced becauseconditioning occurs with smaller cross section polymer compositionswhere heat transfer can occur more rapidly than in larger cross sectioncompositions.

The process of the present invention produces an OPC of the presentinvention that comprises multiple laminated polymer compositions whereinat least one of the polymer compositions is oriented. Desirably,multiple, even all of the polymer compositions comprising the OPC areoriented. OPCs of the present invention generally have a characteristiclamination line where to polymer compositions are adhered together. Thelamination line is generally only apparent under magnification (forexample, 10× magnification). Desirably, the lamination line is only afine feature in the OPC that is unapparent to an unaided eye.Surprisingly, even after drawing, the laminated billet remains in-tactand has properties equivalent to an OPC drawn from a single billethaving dimensions of the laminated billet.

The process of the present invention is useful for creating a largebillet from small dimension billets for the advantage of reducingtemperature conditioning time between extrusion and drawing for thelarge billet. In such a case, the second polymer composition is also abillet. The process offers most advantage in this manner when the largebillet has all cross sectional dimensions in excess of 5 centimeters(two inches), even more so when the large billet has all cross sectionaldimensions of 10 centimeters or more, and yet more so when the billethas all cross sectional dimensions of 15 centimeters or more.

The process of the present invention is also useful for creating abillet comprising a functional skin prior to drawing by using afunctional skin for the second polymer composition. For example, thesecond polymer composition can be a protective covering such as ascratch and mar resistant layer or film, an ultraviolet resistant(absorbent) layer or film, a colored layer or film or a layer or filmoffering any combination of these or other functionalities. Creatingbillets having one or more than one functional skin is desirable innumerous applications. For example, colorant can be concentrated in thefunctional skin where it will be apparent while the billet below thefilm can be free of colorant since it is not seen. As another example,rubber particles or other scratch resistant additives can beconcentrated in a functional skin on a billet where scratch and marresistance is needed rather than wasted inside the core of the billet.

Of course, the process can offer both advantages at the same time bylaminating multiple polymer compositions together wherein at least twoare billets and at least one is a functional skin.

The process of the present invention is also useful for incorporatingrecycled polymer composition into an OPC. Recycled polymer compositioncan include any one or combination of more than one of recycled OPC,recycled billets and other recycled polymer material. In manyapplications the color of an OPC is important, applications such asdecking, fencing, siding and any other exposed application.Incorporation of recycled polymer into an OPC is desirable in order tominimize waste. However, it can be difficult to color match recycledpolymer compositions with “virgin” (non-recycled) polymer composition,particularly when incorporating recycled polymer compositions having adifferent color than the virgin polymer composition or the desired colorof the resulting OPC. One desirable embodiment of the present inventionprecludes any need to color match recycled polymer composition withvirgin polymer composition and thereby facilitates ready incorporationof recycled polymer composition into any OPC. The desirable embodimentsandwiches a recycled polymer composition with virgin polymercomposition in a laminated billet and resulting OPC. Even moredesirably, the process encloses recycled polymer composition with virginpolymer composition along all length dimensions of the OPC and,preferably, the laminated billet.

One way to prepare a laminated polymer billet with recycled polymercomposition sandwiched between virgin polymer compositions is bypreparing a laminated polymer billet having at least three polymercomposition layered such that one polymer composition is an interiorpolymer composition. The interior polymer composition is laminated toboth of the other two polymer compositions and resides between the othertwo polymer compositions.

One way to prepare a laminated polymer billet with virgin polymercomposition enclosing recycled polymer composition along all lengthdimensions is to laminate a recycled polymer composition to and betweentwo virgin polymer compositions that have complementary profiles,meaning that when the virgin polymer compositions are laminated togetherthey cover all length dimension of the recycled polymer composition. Thevirgin polymer compositions are then desirably laminated to each otheras well as the recycled polymer composition.

It is conceived that the virgin polymer compositions achieve theircomplimentary profile after lamination to the recycled polymercomposition by, for example, folding virgin polymer composition thatextends beyond a dimension of the recycled polymer composition over therecycled polymer composition so as to enclose the recycled polymercomposition along all of its length dimension.

A skilled artisan recognizes that many variations of forming a laminatedbillet are possible, including many ways to position a recycled polymercomposition in the laminated billet such that it has minimal appearancein an OPC resulting from drawing the laminated billet. For example, arecycled polymer composition can be one of more than one polymercompositions sandwiched between virgin polymer compositions in anymanner described. Recycled polymer composition can also be visible in alaminated billet if that is desirable.

In a laminated billet, any one or more than one of the polymercompositions can be an oriented polymer composition. In particular, whenthe laminated billet comprises three or more laminated polymercomposition an internal polymer composition can be an orientable polymercomposition.

EXAMPLES

The following examples serve to further illustrate embodiments of thepresent invention.

Comparative Example A Single Large Dimension Polymer Billet

Prepare an orientable polymer composition by combining 54 wt %polypropylene (INSPIRE® D404 resin, INSPIRE is a trademark of The DowChemical Company) and 46 wt % talc (TC-100 From Luzenac) in a 40millimeter (mm) co-rotating twin screw extruder and then pelletize thepolymer composition. Feed polymer and filler at the specified weightratio through standard loss in weight feeders. Melt the polymer in themixing extruder and mix the filler into the polymer matrix to form apolymer/filler mix. Feed the polymer/filler mix from the mixing extruderinto a suitable pumping device (for example, a single screw extruder orgear pump) and then through a multi-hole strand die to produce multiplestrands of the polymer/filler mix. Cool the strands under water and cutthem into pellets.

Prepare a billet from the pellets of orientable polymer composition byfeeding the pellets to an extruder, plasticating the pellets at atemperature of 198° C. (about 30° C. above the softening temperature ofthe orientable polymer composition) and extruding the plasticatedorientable polymer composition through a rectangular billet die havingdimensions of 5.08 centimeters (two inches) wide by 1.52 centimeters(0.6 inches) high. Feed the extruded orientable polymer compositionthrough a calibrator having opening dimensions of 5.08 centimeters (twoinches) by 1.52 centimeters (0.6 inches) to a haul off device (forexample, belt puller) and haul-off the orientable polymer composition ata rate sufficient to neck the composition to a small enough dimension tofit through a solid state drawing die that will be used to draw down thebillet in the next step and long enough extend through the solid statedie to a drawing puller. Upon achieving sufficient length of necked downbillet, progressively slow the haul-off rate to achieve a graduallylarger cross sectional area for the billet until achieving the full 5.08centimeter by 1.52 centimeter cross sectional dimension. When the billetreaches the full cross sectional dimension it contacts the walls of thecalibrator, which smoothes the surface of the billet to a uniformrectangular shape. Cut the billet after achieving a length of billethaving full cross sectional dimensions that is approximately four meters(13 feet) long. Repeat the process for each billet used in the Examplesand Comparative Examples. The billets have negligible void volume.Therefore, any void volume in resulting OPCs is due to cavitation (thatis, OPC void volume is cavitated void volume)

Draw the polymer billets through a solid state drawing die. The solidstate drawing die for use in the drawing process is a proportionaldrawing die, though a proportional drawing die is not necessary for thebroadest scope of the process of the present invention. In aproportional drawing die the shaping channel walls define a polymercomposition drawing path extending from the entrance opening to the exitopening in which all cross sections of polymer composition havesubstantially proportional non-circular cross section shape and have acentroid lying on a substantially straight line (“centroid line”)extending parallel to the drawing direction. All cross sections of theshaping channel are proportional to one another and the shaping channelwalls continually taper towards a centroid line through the shapingchannel. The shaping channel wall on the “sides” of the shaping channel(corresponding to the 1.52 centimeter dimension of the initial billet)taper towards a centroid line of the shaping channel at a 15° angle. Theshaping channel walls on the “top” and “bottom” of the shaping channel(corresponding to the 5.08 centimeter dimension of the initial billet)taper towards the centroid line of the shaping channel at a 4.6° angle.

Draw each billet through the solid state drawing die to form an OPC.Feed the narrow portion of the billet through the drawing die, through a23° C. water spray tank that is 1.5 meters (five feet) long and to abillet puller. Condition each billet to a drawing temperature (T_(d))and set the drawing die to the T_(d). The T_(d) is 15° C. below thesoftening temperature of the polymer composition comprising the billet.Maintain the billet prior to the drawing die and the drawing die at thedrawing temperature throughout the drawing process. Draw the billetthrough the drawing die by gradually increasing the rate (drawing rate)at which the billet puller moves the billet through the drawing dieuntil achieving a drawing rate of 5.8 meters (19 feet) per minute.Increase the drawing rate gradually enough to avoid breaking the OPCexiting the drawing die. During the drawing process, the billetundergoes cavitation as it undergoes orientation.

Example 1 Laminated Billet of Similar Dimension to Comparative Example ABillet

Prepare two initial billets in similar manner as the billet forComparative Example A except by extruding the polymer compositionthrough a die having a height of 6.35 mm to produce a billet havingapproximately half the height (thickness) of the billet of ComparativeExample A.

Prepare a laminated billet by melt-welding two initial billets together.Align two initial billets that are approximately 20 feet long one overthe other on a conveyor system of rollers. Heat the surfaces of the twoinitial billets that face one another (opposing surfaces) to amelt-welding temperature that is approximately 10° C. above theirsoftening temperature using hot air directed at the surfaces. When thesurfaces reach the melt-welding temperature convey the initial billetsso that the surfaces at the melt-welding temperature contact one anotherand compress the initial billets together for approximately 45 secondsby directing them through opposing compressing rollers and then throughpulling belts. The result is a laminated billet comprising two initialbillets melt-welded together. The resulting laminated billet hasdimensions similar to the billet in Comparative Example A.

Draw the laminated billet in like manner as Comparative Example A toproduce an OPC of the present invention comprising two laminated polymercompositions. Surprisingly, the laminated billet produces an OPC withoutfailure of the melt-weld. Moreover, the laminated billet produced an OPChaving similar strength and properties as single polymer compositionbillet of Comparative Example A. Table 1 shows density and splitstrength properties for Comparative Example A (Comp Ex A) and Example 1(Ex 1). The density of the laminated billets prior to drawing is 1.31grams per cubic centimeter.

TABLE 1 Density Split Strength^(a) Sample (g/cubic centimeter) (Newtons)Comp Ex. A 0.83 25 Example 1 0.93^(b) 29 ^(a)Measure Split Strengthaccording to the Split Strength Test described below. ^(b)Example 1 hasa slightly higher density predominately due to lower cavitation as aresult of having a smaller nominal draw ratio (NDR) in the drawingprocess. The laminated billet of Example 1 is slightly less high (thick)than the billet in Comparative Example A. Yet both billets were drawnthrough the same die. The NDR is the ratio of billet cross sectionaldimensions to drawing die exit opening dimensions. A smaller NDRtypically results in less cavitation (higher density). Since Example 1has a smaller billet dimension than Comparative Example A it also wouldbe expected to have a slightly higher density.

Determine Split Strength according the following Split Strength Test.Take a sample of OPC that is 2.54 centimeters wide and 2.54 centimeterslong and 1.27 centimeters thick. On one end of the OPC sample introducea notch extending the width of the OPC and centrally located in thethickness dimension. For Comparative Example A, introduce a notch intoone end by slowly hammering a razor blade into the end extending thewidth of the sample and half-way through the thickness. The notch shouldrun parallel to the length of the sample. Hammer the razor blade inenough to create a 1.27 centimeter (0.5 inch) deep notch. For Example 1,create a notch having the same depth by not heating a segment of thesurfaces in the area of the notch and thereby avoiding melt-weldingwhere the notch is. The melt weld should lie in the plane of the notch.

Drill two 1/16^(th) inch (1.59 millimeter) diameter holes through thesamples and notch that extend from one surface through the opposingsurface of the sample and perpendicular through the notch. The holes arecentered 13 millimeters apart and 3.2 millimeters from the end of thenotched end of the sample. Thread one end of a 24 gauge galvanized steelwire through the hole on one surface and out through the notch and twistto a portion of the wire prior to the hole so as to fasten the wire in aloop through one hole. Repeat with the other end of the wire through theother hole on the same surface of the sample. The sample should have aloop of wire fastened to one half of the sample on the same side of thenotch.

With a second wire, repeat this process on the opposing side of thesample so as to create a metal wire loop fastened to the other half ofthe sample on the opposing side of the notch as the first wire.

Attach the wire loops to opposing grips in an Instron. Pull the wires(and opposing halves of the OPC sample) apart with the Instron at aconstant crosshead speed of 50.8 millimeters per minute (two inches perminute) until the OPC sample splits. Record the maximum force prior tosplitting as the split strength of the sample. Repeat the test with fivesamples and take the average of the maximum force prior to splitting ofthe repetitions to establish a split strength for each of ComparativeExample A samples and Example A samples.

The data from Comparative Example A and Example 1 illustrates that thelaminated billet produced an OPC having similar strength and density asan OPC drawn from a single non-laminated billet. This result issurprising; particularly in view of the fact that it is surprising thelaminated billet merely avoiding failure of the lamination (such asdelamination) during drawing.

Comparative Example A and Example 1 illustrate a non-continuous processwhere billets were extruded in one step and then drawn (Comp Ex A) orlaminated and drawn (Ex 1) in a separate step. Identical results areexpected from a continuous process for both Comp Ex A and Ex 1 where thebillet proceeds directly and continuously from an extruder, throughproper temperature conditioning and then either drawing (for Comp Ex A)or laminating to form a laminated billet followed by drawing (for Ex 1).The benefits of the laminated process are most valuable in a continuousprocess where minimizing the cooling time necessary prior to drawing isvaluable to maximize production rate and minimize the equipmentfootprint (space needed for equipment).

Example 2 Laminated Billet Comprising Recycled Polymer Composition

Prepare a polymer billet of recycled polymer composition in like manneras virgin polymer composition billet by extruding the recycled polymercomposition through an extruder and out a die of desirable dimensions.Obtain the recycled polymer composition, for example, by grinding up anOPC and then feeding the ground up OPC into an extruder in like manneras virgin polymer. Adjustments to ground recycled polymer compositionparticle size and shape can be desirable to optimize properties of theresulting extruded polymer billet.

Prepare a laminated polymer billet and OPC in like manner as Example 1except substitute the recycled polymer billet for one of the initialbillets. Optimally, the recycled polymer billet and initial billet towhich is laminated comprise the same or very similar polymers in orderto optimize strength in the melt-weld.

Draw the resulting laminated billet through a drawing die in like manneras Example 1 to achieve an OPC of the present invention that comprises arecycled polymer composition.

A variation of Example 2 is to laminate the recycled polymer compositionto two initial billets such that the initial billets sandwich therecycled polymer composition to create a three-layer laminated billetand then drawing the three-layer laminated billet to produce an OPC ofthe present invention with an interior recycled polymer composition.

The invention claimed is:
 1. A solid state die drawn large dimensionedoriented polymer composition comprising at least two laminated polymercompositions where at least one of the two laminated polymercompositions is oriented, and wherein all cross sectional dimensions ofthe oriented polymer composition are greater than 1.5 mm, wherein theoriented polymer composition has a density of 0.93 g/cm³ or less.
 2. Theoriented polymer composition of claim 1, wherein the at least one of thetwo laminated compositions that is oriented is cavitated.
 3. Theoriented polymer composition of claim 1, wherein the at least twolaminated polymer compositions differ in at least one characteristicselected from a group consisting of extent of orientation, composition,color, and extent of cavitation.
 4. The oriented polymer composition ofclaim 1, wherein the oriented polymer composition comprises at leastthree laminated polymer compositions with at least one internallaminated polymer composition adhered to the at least two laminatedpolymer compositions and wherein at least one of the at least threelaminated polymer compositions is oriented.
 5. The oriented polymercomposition of claim 1, wherein at least one of the at least twolaminated polymer compositions comprises a recycled polymer composition.6. The oriented polymer composition of claim 1, wherein the orientedpolymer composition has a split strength of at least 29 Newtons.
 7. Asolid state die drawn oriented polymer composition comprising at leasttwo laminated polymer compositions where at least one of the twolaminated polymer compositions is oriented, and wherein the at least twolaminated polymer compositions are melt-welded together as evidenced bya melt-weld line at the interface of the at least two laminated polymercompositions, wherein the oriented polymer composition has a density of0.93 g/cm³ or less.
 8. The oriented polymer composition of claim 7,wherein the at least one of the two laminated compositions that isoriented is cavitated.
 9. The oriented polymer composition of claim 7,wherein the at least two laminated polymer compositions differ in atleast one characteristic selected from a group consisting of extent oforientation, composition, color, and extent of cavitation.
 10. Theoriented polymer composition of claim 7, wherein the oriented polymercomposition comprises at least three laminated polymer compositions withat least one internal laminated polymer composition adhered to the atleast two laminated polymer compositions and wherein at least one of theat least three laminated polymer compositions is oriented.
 11. Theoriented polymer composition of claim 7, wherein at least one of the atleast two laminated polymer compositions comprises a recycled polymercomposition.
 12. The oriented polymer composition of claim 7, whereinthe oriented polymer composition has a split strength of at least 29Newtons.